Waves Flashcards
What is a diffraction grating used for in astronomy?
To split up light from star to obtain line absorption specra, revealing the elements present in the star.
What is X-ray crystallography?
A technique where x-rays are directed at a thin crystal sheet, acting as a diffraction grating to form a diffraction pattern.
How is the refractive index (n) calculated?
n=c/cs, where c is the speed of light in a vacuum and cs in the speed of light in the substance.
What occurs when the angle of incidence reaches the critical angle?
The angle of refraction in exactly 90, and the light is refracted along the boundary.
What is total internal reflection?
It occurs when the angle of incidence is greater than the critical angle and n1>n2.
What are optical signals used for?
To carry information in the form of light signals.
What is the role of cladding in optical fibers?
To provide lower optical density surrounding the core, allowing TIR to occur and protect the core.
How can material dispersion be prevented?
Use monochromatic light
How can model dispersion be reduced?
Make the core of the fibre very narrow.
What is the purpose of an optical fibre repeater?
To regenerate the signal on its way to its destination.
What is dispersion in optical fibres?
It causes pulse broadening where the received signal is broader than the original transmitted signal.
Equation for speed of wave
C= f × wavelength
